Hanger arm mechanism in dental lighting equipment

Abstract

A hanger arm mechanism to hold a lamp head vertically rotatably in dental lighting equipment is directed to a mechanism designed to rotate the lamp head around the axis shaftline of the hanger arm and to stop the same in a desired position, with the result that the field of lighting of the shadowless lamp mounted inside the lamp head can freely be changed in the range of rotation of the lamp head without making the patient turn his head.

We claim: 
     
       1. A hanger arm mechanism in dental lighting equipment including a horizontally movable arm, a vertically movable arm, a hanger arm and a lamp head, said mechanism being characterized in that said hanger arm comprises: a hanger arm body made of a pipe member;   a rotary member, said rotary member being provided in the front portion of said hanger arm body and vertically movable with the lamp head and being inserted into and coupled to said hanger arm body so as to be freely rotatable about the axis shaft line of the hanger arm body; and   a friction adjusting member, said member being adapted to change the rotating slide contact portion formed in said rotary member and the friction force of said contact portion for affecting rotation of said rotary member under pressure contact friction.   
     
     
       2. A mechanism according to claim 1, wherein said rotary member comprises: a hollow cylinder, said cylinder being provided in the front part with a lamp head fitting and in the rear part with a flange;   said hanger arm body behind said rotary member is provided with a cylindrical fixed member, said fixed member being fitted in the front part with a ringlike flange member to thereby come into slidable contact with said flange to constitute a rotating slide contact portion;   said rotary member being enveloped over the outer circumference thereof with a compression spring to thereby produce resilient force for drawing out said flange in the direction of the axis shaftline of said hanger arm and for pushing in said ringlike flange member in the direction opposite thereto so as to constitute a friction adjusting member adapted to change the frictional force of said rotating slide contact portion.   
     
     
       3. A mechanism according to claim 2, wherein said lamp head fitting member is threadedly connected to the front part of said rotary member, and said ringlike flange member is threadedly connected to the front part of said fixed member.